Flashing incandescent lamp



0a. 31, 1944. w. F. MacGREGoR 2,361,486

FLASHING INCANDES CENT LAMP Filed Jan. 26, 1944 lnven tor": WiLLi'am F. MacGT'egoT',

His Airborneg.

Patented Oct. 31, 1944 2,361,436 msumc. INCANDESCENT LAMP William F. MacGregor, Toronto, Ontario, Canada,

assignor to General Electric Company, a corporation of New York Application January 26, 1944, Serial No. 519,766 In Canada August 18, 1943 4 Claims.

This invention relate to electric incandescentlamps and particularly to flashing lamps wherein the filament is automatically energized intermittently.

It has been. previously proposed to construct an incandescent filament lamp with a bi-metal element adjacent the filament and arranged in the circuit to the filament in such a manner that when the lamp is cold the circuit is complete and filament is energized but when the filament heats up the bi-metal element bends to break the circuit and deenergize-the filament, the sequence of operations being continued automatically. Such lamps are desirable for signalling purposes on account of the conspicuousness of a flashing lamp and particularly because of the longer battery and lamp life obta.ned for a given overall period of operation.

My invention relates to constructional features of a lamp as above described whereby a rugged mounting of the parts is obtained to withstand the vibration and shocks encountered in use and whereby cheapness of manufacture and reliability of operation are also obtained.

For a complete understanding of my invention, reference is had to the following detailed description of an embodiment of my invention in which Fig. 1 is a perspective view with the base shown partly in section; and Fig. 2 is a view from a position approximately at right angles to Fig. l but with the base omitted and the bulb shown fragmentarily.

The lamp shown in the drawing comprises a bulb it with a neck ll having a butt seal i2. The butt seal is formed by fusing to the end of the neck of the bulb, the-end of a tube of the same diameter which tube is used as an exhaust tube, and sealing in the lead wires for the lamp' filament at the point of fusion. The butt seal is known in the art in small size lamps and is well adapted for cheap manufacture on a machine such as shown in .Patent 1,742,153, Stiles et al., dated December 31, 1929.

The mount comprises three support wires M, It and it fused through a glass bead H with the wires equally spaced from one another, that is arranged in the bead at the three corners of an equilateral triangle. The upper end-oi the sup port wire M is bent just above the head I! to extend at. right angles to itself as indicated at it. The support wire l5 extends above the bead ii a greater extent than the wire l4 and ha its end bent as indicated at i9 to be parallel to the bent end i8. The support wire l6 extends abovethe head I! to a point intermediate the bent ends tends transversely of the bi-metal strip about the middle portion thereof and spaced in close proximity thereto. The bl-metal 2| is so ar-.

ranged that when it is warmed up by the heating of th filament it bends away from the end it. The mount as above described is a compact arrangement of parts which is readily manufactured and its overall transverse dimensions aresuch that it will pass easily through the hook it of the bulb. The ends of the support wires Hi, l5 and i6 below'the bead extend through the seal 52 at the lower end of the neck ll are spaced degrees apart therein, and are fused therein at the time the seal is made. The mount with the triangular arrangement of the support wires extending from the seal forms a strong support for the pants not easily damaged by shocks.

To the neck of the bulb is applied a two contact shell. shell type with the extension of the support wire it outside the seal soldered to the shell 22 and with the extension of the support wire it outside the seal soldered to the center contact 23. The support wire it is supported in the seal but has no external electrical connection.

The operation of the lamp will be apparent from the above description. circuit leading to the contacts 22 and 23 is closed the circuit through the lamp is completed from contact. 2 3 through support wire it, bi-metal strip 2i, arm is, support wire l5, filament 20 and support wire it to the shell contact 22. The filament lights up and the heat therefrom causes the bil metal to bend and break contact with the arm is thereby breaking the circuit. When the filament cools down the bi-metal also cools after a time lag and again completes the above described circuit at the arm H9. The filament is thus lighted interm.ttently as long as the external circuit remains closed.

The lamp described is of a sturdy construction, reliable in operation and adapted to low cost manufacture. While I have described in detail a specific form of my invention, I do not desire to be limited thereto but to include all modifications This is shown as of the known screw- When the electrical I spaced support wires fused in a glass bead, a- I lamp filament arranged between a pair of the support wires and lying substantially transverse to the length thereof, a bi-metal strip arranged between another pair of said wires and lying substantially lengthwise thereof and with its middle portion closely adjacent to the filament, the support wires below the bead extending through the neck and sealed in circumierentially spaced relation in a butt seal at the end thereof.

2. A device of the class described comprising a bulb having a neck portion and butt sealed at the end of the neck, three support wires fused in the seal in spaced relation about the neck and extending into the bulb, an insulating bead fused to the wires at a point above the seal holding them in spaced parallel relation, the first of said support wires terminating a short distance above the bead, the second of said support wires projecting substantially above the upper end of the first support wire, a strip of bi-metal having one end welded to the end of said first wire in such a manner that it makes contact with the end of the second wire and bends out of contact therewith when heated, the third support wire projecting above the bead to a point intermediate the ends of said first and second wires, a lamp filament .welded to the end of the third wire and to an intermediate point on the second wire and lying transverse to and spaced close to an intermediate point of the bi-metal, the endsof the first and third wires projecting outside the seal and con nected to circuit making contact.

3. A device of the class described comprising a 40 glass bulb having a neck portion and butt sealed at the end of the neck, three support wires fused in the seal at equally spaced points circumferentially thereof and extending into the bulb, a glass bead fused to the wires at a point spaced from the seal and holding them in spaced parallel relation, the first of said support wires terminatinga short distance beyond the bead and having its end bent substantially parallel to the bead, the second of said support wires extending substantially farther into the bulb and having a bent end lying parallel to and spaced from the bent end of the first wire, a strip of bi-metal having one end welded to the bent end of said first wire in such a, manner that its other end is in contact with the bent end of said second wire when cold and bends out of contact therewith when heated, the third of said support wires extending beyond the bead, and a lamp filament extending between said second and third support wires and lying adjacent the bi-metal, the ends of the first and third supp rt wires outside the seal being connected to circuit making contacts.

4. A flashing incandescent lamp comprising a sealed bulb, three spaced support wires extending into the bulb in the same direction and terminating at different levels spaced apart substantial distances, the intermediate wire terminating at a point approximately midway between the shorter and longer wires, a bi-metallic strip extending longitudinally between the ends of the shorter and longer wires, said strip being secured to the end of the shorter wire and engaging the end of the longer wire when it is cold, 9. filament extending laterally between and electrically connected to the end of the intermediate wire and a point on the longer wire, and a pair of external contacts connected respectively to the said shorter and intermediate wires.

WILLIAM F. MACGREGQR. 

